[Nek5000-users] Non-dimensional wall distance y+ and Re:Total energy and wall gradients

[nek5000-users at lists.mcs.anl.gov]

Howdy list,

last week, I finished writing the attached additions to userchk which 
I'd like to share. The code computes shear stress, nearest grid point 
distance and y+ on all wall faces - maybe this also helps JC with his 
wall normal gradients.
Wall distance is saved in passive scalar 1 and y+ in passive scalar 2. 
Those values are only stored on the wall faces, and are zero everywhere 
else in the domain.

Shear stress is computed as follows:
1) Compute the gradient tensor (evaluated at the wall) and multiply with mue
S_ij=mue delta_j u_i

2) Project on wall normal direction (n_j is the vector normal to the 
surface of interest, pointing away from it)
R_i=S_ij n_j

3) Vector sum
tau_wall=sqrt(R_i R_i)

For wall distance computation, I dug out a dusty routine from turb.f, 
hoping it's not on the silent list of soon to be killed or altered nek 
subfunctions.

Markus